Solve Equations 2x+3y-z=5,3x+2y+z=10,x-5y+3z=0 using Elimination method
Solution:
Total Equations are `3`
`2x+3y-z=5 -> (1)`
`3x+2y+z=10 -> (2)`
`x-5y+3z=0 -> (3)`
Select the equations `(1)` and `(2)`, and eliminate the variable `z`.
`2x+3y-z=5` | ` xx 1->` | | `` | `2x` | `+` | `3y` | `-` | `z` | `=` | `5` | `` |
| | + | |
`3x+2y+z=10` | ` xx 1->` | | `` | `3x` | `+` | `2y` | `+` | `z` | `=` | `10` | `` |
| | |
|
| | | `` | `5x` | `+` | `5y` | | | `=` | `15` | ` -> (4)` |
Select the equations `(2)` and `(3)`, and eliminate the variable `z`.
`3x+2y+z=10` | ` xx 3->` | | `` | `9x` | `+` | `6y` | `+` | `3z` | `=` | `30` | `` |
| | − | |
`x-5y+3z=0` | ` xx 1->` | | `` | `x` | `-` | `5y` | `+` | `3z` | `=` | `0` | `` |
| | |
|
| | | `` | `8x` | `+` | `11y` | | | `=` | `30` | ` -> (5)` |
Select the equations `(4)` and `(5)`, and eliminate the variable `x`.
`5x+5y=15` | ` xx 8->` | | `` | `40x` | `+` | `40y` | | | `=` | `120` | `` |
| | − | |
`8x+11y=30` | ` xx 5->` | | `` | `40x` | `+` | `55y` | | | `=` | `150` | `` |
| | |
|
| | | | | `-` | `15y` | | | `=` | `-30` | ` -> (6)` |
Now use back substitution method
From (6)
`-15y=-30`
`=>y=(-30)/(-15)=2`
From (4)
`5x+5y=15`
`=>5x+5(2)=15`
`=>5x+10=15`
`=>5x=15-10=5`
`=>x=(5)/(5)=1`
From (2)
`3x+2y+z=10`
`=>3(1)+2(2)+1z=10`
`=>1z+7=10`
`=>1z=10-7=3`
Solution using Elimination method.
`x=1,y=2,z=3`
This material is intended as a summary. Use your textbook for detail explanation.
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